Sant'Andrea Island, on which its namesake fort stands, owes its name to the Cloister of Sant'Andrea, erected in 1199 on nearby Certosa. The defensive structure, which was recently restored, dates back to the XVI century. During the days of the Republic of Venice it was a strategic extension of the all gone Fort of San Nicolò of Lido, to which it was connected by long chains which, once stretched, would prevent enemies from entering.
The entire structure, except for the old look-out tower, is by architect Michele Sanmicheli. Despite its military use, its refined appearance was a preview for sailors arriving from the sea of the splendour and power of Venice. An interesting description of the Fort is made in the writings by Giacomo Casanova, who was imprisoned here in 1743.